A 70 MHz - 4.1 GHz 5th-Order Elliptic gm-C Low-Pass Filter in Complementary SiGe Technology

We present the first demonstration of a continuous-time, fifth-order, elliptic, g
_m
-C low-pass active filter in 0.25 mum complementary (npn + pnp) silicon-germanium (C-SiGe) heterojunction bipolar transistor (HBT) technology. This C-SiGe technology features npn SiGe HBTs with peak f
_T
and f
_max
of 170 GHz and 170 GHz, respectively, as well as pnp SiGe HBTs having f
_T
and f
_max
of 90 GHz and 120 GHz, respectively. This C-SiGe active filter was implemented with Voorman transconductors (Voorman, 2000) to fully exploit the complementary high-speed npn and pnp SiGe HBTs. The circuit occupies an area of 0.82 mm
²
, and exhibits a filter cut-off frequency of 4.1 GHz. This C-SiGe active filter achieves a record continuous tuning range between 70 MHz and 4.1 GHz, attains an output noise power spectrum density (PSD) of -143 dBm/Hz, and operates off a 3.5 V supply, with a total power consumption of 100 mW at the maximum bandwidth of 4.1 GHz